Fixed some errors in shadow rift

Two variables were never used.
The game tried to send a message to players if they tried to cast shadow
rift in a zone that does not allow shadow rift like guildhalls and
bosszones, but the server never had a target so it caused a error
message.
Return outside for loop

Should return only once instead of once for every caster
Removed who from CanHavePlayerPortal

'who' was never used in CanHavePlayerPortal so it was removed
Removed comment
Merge pull request #186 from broodhill/Shadowrift-fixes

Fixed some errors in shadow rift